if you can't find it at ifixit.com then I know welovemacs.com sells original Mac OS install discs for many different models including iBook G4, though not necessarily cheap. I don't know of a similar vendor in Canada.
take a look http://welovemacs.com/osx1031037.html
specifically I see here's 10.3.2 for iBook G3/G4 install discs: http://welovemacs.com/6914946a.html
as mentioned above, you can run up to OS 10.4.11 on the iBook G4, so I think you're better off just installing this later version if you already have it